统计数据是基于周期的。如果一天过去了，那么这段时间（开始和结束）也会提前一天。所以，完全正常的是，您的访问总次数从一天到另一天都在变化，因为时间段也发生了变化。

例如：假设您的网站每隔一天接收60位唯一身份访问者。您今天（13-08-2012）查看了Google Analytics并查看了1860次访问。这是从13-07到12-08期间唯一访客总数。

但是可以说，您的网站今天只能收到10位访问者。明天（14-08），您将看到您的总唯一访客从1860年降至1810年，因为这段时间将从14-07年至13-08年。

I check my Google analytics on a regular basis to obviously see my daily hits and for some reason my UNIQUE VISITORS count dropped from 1770 to 1730 over a day. How this is possible?

I started to notice this about a week ago when I saw that my UNIQUE VISITORS count wasn't going over 1800 (which it should have considering the visits I receive). I receive an average of about 60 unique VISITS a day but even if it was 0 unique visits a day, it doesn't sound logical that my overall UNIQUE VISITORS count would drop.

Now I can't take GA seriously anymore ... Anyone have this problem before and / or could shed any light on the matter?

The statistics are period based. When a day passes, the period (begin and end) advances a day as well. So is perfectly normal your total unique visits changes from one day to another, because the period changed too.

For example: lets suppose your site receive 60 unique visitors every single day. You check your Analytics today (13-08-2012) and see 1860 visits. That amout is the total unique visitors for the period from 13-07 until 12-08.

But lets say that your site receives only 10 visitors today. Tomorrow (14-08) you will see your total unique visitors drops from 1860 to 1810, because the period will be from 14-07 until 13-08.